Inhibitory effect of tranilast on transforming growth factor betaexpression in corneal fibroblasts derived from granular corneal dystrophy type II

Abstract

Purpose: To investigate the effects of tranilast on expression of transforminggrowth factor beta-induced protein (TGFBIp) in wild-type (WT) and homozygous (HO) granular corneal dystrophy type II (GCD 2) corneal fibroblasts

Methods: Corneal fibroblasts were incubated with tranilast (0.01, 0.025, 0.05,0.1, 0.25, 0.5 or 1.0 mM), after which cell proliferation and cytotoxicity were measured. Changes in expression of TGFBIp and TGFBI mRNA after application of tranilast in WT and HO GCD2 corneal fibroblasts co-treated with TGF-β (5.0 ng/mL) were examined by Western blot analysis and real-time polymerase chain reaction, respectively. Furthermore, effects of tranilast on type I collagen, phosphorylated Smad2 (pSmad2) and pSmad3 expression, wound healing assay of corneal fibroblasts, alpha-smooth muscle actin (α-SMA) expression, and integrin expression were evaluated.

Results: Tranilast decreased the number of viable corneal fibroblasts, but didnot induce cytotoxicity. TGF-β increased expression of TGFBIp and TGFBI mRNA in WT and HO GCD2 corneal fibroblasts. However, application of tranilast in corneal fibroblasts co-treated with TGF-β reduced levels of TGFBIp and TGFBI mRNA. TGF-β increased expression of type I collagen and pSmad2 in WT and HO GCD2 corneal fibroblasts, but pSmad3 in HO GCD2 corneal fibroblasts. Application of tranilast reduced levels of type I collagen and pSmad2 in WT and HO corneal fibroblasts co-treated with TGF-β, and pSmad3 in HO corneal fibroblasts. Tranilast delayed wound healing by inhibiting expression of α-SMA and integrins.

Conclusions: Tranilast can be used for delaying or prevention of recurrence of corneal opacity in TGFBI-linked corneal dystrophies by inhibiting TGF-β signaling pathway.

Keywords: 480 cornea: basic science • 533 gene/expression • 739 transcription factors